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(C) (i), (ii) and (iv)

In the given reaction, there is addition of oxygen to iron metal and it is oxidised. Also, there is removal of hydrogen from the water and thus, water is reduced. A substance which causes oxidation of other chemical species in a chemical reaction and itself undergoes reduction, is known as an oxidising agent. Thus, in given reaction, water is acting as an oxidising agent.

1. (i) TRUE

2. (iv) All of the above

3. (iv) All of the above

4. (iv) Corrosion can take place in vaccum

5. (iv) All of the above

1. (i) CuSO₄

2. (i) Loss the electrons

3. (iv) Copper Sulphat

4. (ii) Displacement reation

5. (ii) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

The process of making the number of different types of atoms equal on both sides of an equation is called the balancing of the equation.

(i) 4Al + 3O₂ → 2Al₂O₃, Aluminium oxide 

(ii) 3Fe + 4H₂O → Fe₃O₄ + 4H₂, Ferric oxide 

(iii) Ca + 2H₂O → Ca(OH)₂ + H₂ because hydrogen sticks to calcium.

(C) (i) and (iii)

The given reaction is a displacement reaction as hydrogen (H) in NH3 is displaced by oxygen (O). It is also an example of redox reaction as oxidation and reduction reaction occur simultaneously.

The elements or compounds which occur naturally in the earth's crust are known as minerals. 

The mineral from which a particular metal can be profitably extracted is called ore. 

Gold is very less reactive whereas aluminium is a very reactive element. Therefore, aluminium reacts with other elements or compounds more than gold. Thus, aluminium occurs in combined state while gold occurs in free state

1. (iv) Oxidation

2. (i) TRUE

3. (ii) Brown

4. (iii) Oxidation

5. (ii) It gives oxygen

All the combustion reactions are exothermic reactions.

The substance which gets reduced is the oxidizing agent.

(i) 4Al + 3O₂ →  2Al₂O₃, Aluminium oxide 

(ii) 3Fe + 4H₂O → Fe₃O₄ + 4H₂, Ferric oxide 

(iii) Ca + 2H₂O → Ca(OH)₂ + H₂, because hydrogen sticks to calcium.

(a) When manganese dioxide (MnO₂) is heated with aluminium powder, displacement reaction takes place, and manganese is obtained as the product along with aluminium oxide. It is an exothermic reaction and hence Mn is obtained in molten form.

3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(s) + heat

(b) Iron (III) oxide is heated with aluminium powder to form iron and aluminium oxide. This is another example of a displacement reaction and is highly exothermic. This reaction is also known as thermit reaction.

Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + Heat

(i) Mercury is a metal which does not stick to glass as mercury lacks adhesive forces. 

(ii) Zinc Oxide is amphoteric in nature which means it can act as an acid as well as a base in a chemical reaction depending upon the reaction conditions. 

(iii) A pure metal will be deposited at cathode because cathode is a negative electrode and hence it attracts the positive metal ions from the electrolyte. 

(iv) Carbon Monoxide will change the color of the blue litmus if the litmus paper is moist as carbon monoxide will dissolve in the water molecules to form weak acid.

i. Fe + S → FeS 

In this reaction, Iron (Fe) undergoes oxidation and sulphur. (S) undergoes reduction.

ii. 2Ag₂O → 4Ag + O₂↑

In this reaction, reduction of Ag₂O takes place.

iii. 2Mg + O₂ → 2MgO

In this reaction, oxidation of Mg takes place.

NiO + H₂ → Ni + H₂O

In this reaction, reduction of NiO takes place and oxidation of H₂ takes place.

The three properties of sodium are as follows: 

1. Sodium is very soft in nature and it can be easily cut with the help of a knife. 

2. It is non-sonorous metal which means it does not make sound on being hit by hard object. 

3. It has low melting and boiling points

Since ore A gives CO₂ and ore B gives SO₂. 

Therefore, ores are MCO₃ and MS. 

A can be obtained as:

\(MCO_3\overset{Calcination}\rightarrow MO + CO_2\)

\(MO+C\overset{Reduction}\rightarrow M+CO\)

B can be obtained as:

\(2MS+3O_2\overset{Roasting}\rightarrow2MO+2SO_2\)

\(MO +C\rightarrow M+CO\)

In the first reaction zinc is more reactive than copper and hence the above reaction is possible as zinc can replace copper from copper sulphate to form zinc sulphate. 

In the second reaction, it is known that iron is less reactive than zinc and hence iron cannot replace zinc from zinc sulphate.

The substance which gets oxidized is the reducing agent.

Since the ore on heating in air gives Sulphur dioxide which means that the ore is a sulphide ore. The various methods involved in the extraction of metals from sulphide ores are as follows: 

1. The ore is concentrated by the process of froth flotation to remove the impurities. 

2. The concentrated ore is then heated in presence of air to convert the ore to corresponding metal oxide. 

3. The metal oxide is then made to react with carbon to reduce the metal oxide to corresponding metal. 

4. The metal is then purified by electrolytic reduction

Reduction means gaining one or more electrons.

When hydrogen gas is passed over hot copper oxide, the black coating on the surface turns brown as the reverse reaction takes place and copper is obtained.

Reducing agent: A reducing agent is an element that loses electrons. 

The reducing agent means to loose electrons; it is said to have been oxidized. 

The element which undergoes oxidation (gets oxidized) is called reducing agent. 

a) NH₃ is reducing agent 

4NH₃ + 5O₂→ 4NO + 6H₂O 

In the given reaction, nitrogen is oxidized to NO by gaining oxygen atom. Thus, NH₃ is reducing agent as it undergoes oxidation. 

b) F₂ is reducing agent 

H₂O + F₂→ HF + HOF 

In the given reaction, F₂ is oxidized to HOF by gaining hydrogen atom. Thus, F₂ is reducing agent as it undergoes oxidation.

(c) CO is reducing agent

Fe₂O₃ + 3CO → 2Fe + 3CO₂ 

In the given reaction, CO is oxidized to CO₂ by gaining oxygen atom. Thus, CO is reducing agent as it undergoes oxidation. 

(d) H₂ is reducing agent 

2H₂ + O₂→ 2H₂O 

In the given reaction, 2H₂ is oxidized to 2H₂O by gaining oxygen atom. Thus, 2H₂ is reducing agent as it undergoes oxidation.

Oxidizing agent: An oxidizing agent is an element that gains electrons. Since, the oxidizing agent means to gain electrons; it is said to have been reduced.

The element which undergoes reduction (gets reduced) is called oxidizing agent. 

(a) Pb₃O₄ is reducing agent 

Pb₃O₄ + 8HCl → 3PbCl₂ + Cl₂ + 4H₂O

In the given reaction, Pb₃O₄ loses oxygen and reduces to PbCl₂. Thus, Pb₃O₄ is an oxidizing agent as it undergoes reduction. 

(b) O₂ is oxidizing agent 

2Mg + O₂→ 2MgO 

In the given reaction, O₂ is reduced by losing oxygen atoms. Thus, O₂ is an oxidizing agent as it undergoes reduction. 

(c) CuSO₄ is oxidizing agent 

CuSO₄ + Zn → Cu + ZnSO₄ 

In the given reaction, CuSO₄ is reduced to Cu by losing oxygen atoms. Thus, CuSO₄ is an oxidizing agent as it undergoes reduction.

(d) V₂O₅ is oxidizing agent 

V₂O₅ + 5Ca → 2V + 5CaO 

In the given reaction, V₂O₅ is reduced to V by losing oxygen atoms. Thus, V₂O₅ is an oxidizing agent as it undergoes reduction. 

(e) H₂O is oxidizing agent 

3Fe + 4H₂O → Fe₃O₄ + 4H₂

In the given reaction, H₂O is reduced to H₂ by losing oxygen atoms. Thus, H₂O is an oxidizing agent as it undergoes reduction. 

(f) CuO is oxidizing agent 

CuO + H₂→ Cu + H₂O 

In the given reaction, Cu is reduced to Cu by losing oxygen atom. Thus, CuO is an oxidizing agent as it undergoes reduction.

(i) – (j)

(ii) – (g)

(iii) – (f)

(iv) – (k)

(v) – (b)

(vi) – (h)

(vii) – (a)

(viii) – (d)

(ix) – (c)

(x) – (e)

(xi) – (i)

(xii) – (i)

(a) When copper powder is heated in the presence of air (oxygen), cooper reacts with oxygen to form copper oxide. The copper oxide formed is black in colour. The black colour is formed because the oxidation of copper takes place. 

(b) The black substance formed is copper oxide. 

(c) The chemical equation of the reaction that takes place is given below:

2Cu + O₂→ 2CuO

The colour formed on the surface of copper powder when it is heated in a china dish is black. Oxidation of copper takes place. As a result, copper oxide is formed which is black in colour.

(a) When copper powder is heated in the presence of air (oxygen), copper reacts with oxygen to form copper oxide. The copper oxide formed is black in colour. The black colour is formed due to the oxidation of copper takes place.

The chemical equation of the reaction that takes place is given below:

2Cu + O₂→ 2CuO

Copper oxide

(b) When hydrogen gas is passed over hot copper oxide, the black coating on the surface turns brown as the reverse reaction takes place and copper is obtained.

The reaction that takes place is:

CuO + H₂ → Cu + H₂O

Spore formation is a common method of asexual reproduction in many lower forms of life, like bacteria, fungi etc. It occurs mostly during unfavourable conditions such as extreme heat, dryness, etc. The spores are asexual reproducing bodies enclosed in a thick-walled structure called sporangium. On the return of favourable conditions, the sporangium wall bursts and the spores are released.

Production of offspring by a single parent without the formation and fusion of gametes are called asexual reproduction. 

Characteristics of asexual reproduction. 

1. It is repaid mode of multiplication. 

2. Cell division takes place either mitotically or amitotically. 

3. The new individuals produced after cell division are always genetically identical or clone to their parents. 

4. A single parent is involved, i.e opposite sexes are not involved. 

5. It does not involve the fusion of gametes.

In multiple fission, the nucleus divides several times simultaneously or successively into a number of daughter nuclei and then the cytoplasm divides into as many cells as there are nuclei, each cell containing a nucleus. It is the common a form of asexual reproduction in certain acellular organisms.

When Zinc is added to a solution of iron (II) sulphate, Iron is displaced by FeSO₄.

Zn(s) + FeSO₄(aq) ➝ ZnSO₄(aq) + Fe(S)

Yes. Binary fission and budding do not involve any variations, also these involve single parent.

(i) These metals get corroded. Silver forms black Ag₂S (silver sulphide) and copper form greenish layer of basic copper carbonate CuCO₃. Cu(OH)₂. 

(ii) Tamarind contains acid which reacts with basic copper carbonate and product gets dissolved and removed from copper vessel. 

(iii) Aluminium forms oxide layer on its surface which does not further react with air.

(a) These metals are extracted by electrolytic reduction, e.g. aluminium is obtained from bauxite by electrolytic reduction. 

(b) (i) Steel is made up of iron and carbon. 

(ii) Brass is made up of copper and zinc.

i) Human population has increased drastically over the years. 

According to the data, the human population is doubling every 35 years so we need a way or a method that could provide full stop solution or that could prevent this explosion of population. The Methods that could help in controlling the overpopulation or the population explosion are considered as population control. Population control doesn't mean that we need to kill people or remove population already present on the earth It is a way in which the population or we should say the coming population is planned or it is a planned control of population. 

ii) Contraceptives are the most used and the safest methods of birth control. Contraceptive includes the use of condoms, UID and other surgical methods that could provide a method to avoid unwanted pregnancy. 

Using contraceptives reduces the risk of STD. 

Pregnancy at an early stage of a woman could adversely affect her body and her mind so to prevent that contraceptives are used. To control the exploiting population contraceptives play a major role.

Calcium starts floating because the bubbles of hydrogen gas formed sticks to the surface of the metal.

Ca + 2H₂O → Ca(OH)₂ + H₂

Al burn in air at high temperature with the evolution of much heat.

Reduction. is used for obtaining a metal from its oxide

(d) Non-metals are unable to react with water

(c) Metalloids

Chemical properties of metals – Metals react with air, water, acid and form many chemical substances.

(a) Reaction with air:

Metals form their oxides when react with oxygen present in air. Metals + Oxygen → Metal oxides When ribbon of magnesium (Mg) is bum, it converts into white ash. When this ash is dissolved in a test tube with water and tested with a red litmus paper, it converts and turns into blue. Hence, it is proved that this solution (oxide) is alkaline in nature. In the same way copper and aluminium make their oxides due to which utensils of metals look dirty and non lustrous.

(b) Reaction with water:
They form metal hydroxide and release hydrogen. Sodium (Na)+ Water (H₂O) → Sodium hydroxide (NaOH) + Hydrogen (H₂)
When a very small piece of (Na) sodium is dried in a filter paper and then put into a beaker filled with water. It seems that piece of (Na) moves fast as it forms sodium hydroxide and hydrogen reacting with water. As (Na) is very reactive hence it is kept dip in kerosene, if it is kept open it bums with oxygen and reacts with water.
(c) Reaction with acid:
They produce hydrogen gas while reacting with acid.

Chemical properties of non- metals:

(a) Reaction with air: Non metals form their oxides when react with air (Oxygen). These oxide are acidic in nature. Take some powder of sulphur in a metal lid of a bottle and heat it. Wind this metal lid with a metal wire as the sulphur burn took into a gas jar cover it by a lid so the gas not to be let out. Now pour some water into a gas jar and shake it well, test the solution with blue litmus paper, it turns red. It proves that the solution is acidic. Sulphur (S) + Oxygen (O₂) → Sulphur dioxide (SO₂) Sulphur
powder reacts with oxygen which is an acidic oxide of non-metal.
(b) Reation with water: Generally non-metal do not react with water or steam, hence phosphorous are kept in water.
(c) Reaction with acids: Most of the non-metals do not react with dilute acids but sulphur react with concentrated nitric acid and form sulphur – dioxide, nitrogen oxide and water.

Lithium, Sodium and Potassium.

Uses of non metals:

1. Hydrogen and carbon are the essential constituents of the cells of all living beings. Without these elements life is not possible. Further more, carbon in the form of coal is used for generating heat energy for houses as well as factories.
2. Nitrogen in the form of fertilizers is essential for growth and development of plants. Urea and calcium, ammonium nitrate are common fertilizers used by farmers.
3. Oxygen is absolutely essential for the respiration of all kinds of plants and animals. It is also used in manufacture of steels and for artificial respiration on high altitudes, in space and deep sea diving.
4. Silicon is used for making microchips and all kinds of electronic goods.
5. Phosphorus is used in match industry and fertilizers.
6. Sulphur is used for making fire crackers, gun powder and sulphuric acid.
7. Chlorine is used in the disinfection of drinking water.
8. Iodine dissolved in alcohol (tincture iodine) is antiseptic in nature and is used in dressing wounds.
9. Helium is used in baloons.
10. Argon is used in electric lights and advertisement signboards. Neon is also used in advertisements signboards and for lightning.

The material which show brightness on surface and reflect the light are called lustrous material.

Iodine has lustrous surface.

Physical properties of non-metals: 

1. They are non lustrous. 

2. They are non sonorous. 

3. They are soft. 

4. They does not show malleability and ductility. 

5. They are bad conductors of heat and electricity.

Three properties of sodium are :

(i) Sodium is so soft that it can be cut with a knife.

Physical properties of metal:

(a) State: Most of the metals are found in solid state at normal temperature except mercury (Hg) which is found in liquid state at normal temperature.
(b) Colour: Mostly metals are grey in colour.
(c) Lustre: Most of the metals are lustrous. They are capable of reflecting rays of light from their upper surface therefore, they are lustrous such as gold, silver, copper, aluminium.
(d) Hardness: Most of the metals are hard. Hardness of different metals are different. Sodium and potassium are less hard compared to other metals.
(e) Sonorous: When metals are struck with other hard metals or objects then a special sound is produced, this property is called sonorous. Due to this property of metals they are used to manufacture bell and music instrument etc.
(f) Density: Generally metals have high density. Things made of metals are heavy so when they put in water they sink while those have less density will float in water such as sodium (Na) and potassium (K) etc.
(g) Melting Point: That temperature at which solid changes into liquid state is called melting point of that object. Due to hardness of solid their melting point is high such as iron (Fe). The melting point of iron is 1593°C while galium is exception it melts just by putting it on hand palm as its melting point is very low.
(h) Heat conductivity: When a rod of steel is heated, after sometimes it becomes hot while a wooden rod when submerged in hot water does not get heated. Silver (Ag) is the best conductor while lead (Pb) is the least conductor. This is the reason that cooking utensils are made of metals and their handles are made of non-conductors like wood, plastic etc.

1. Malleability: Metals are spread on beating. Hence by the force of hammers they are converted into sheets.
2. Ductility: When they are stretched, convert into wires. This property of metals is called ductility.

(k) Electricity conductivity: Metals allow electricity to pass through them. This property is called conductivity of electricity. Silver is the best conductor of electricity. Hence, those objects which are hard, lustrous, sonorous, ductile, malleable, and good conductor of heat and electricity are called metals.
Physical Properties of Non-Metals:

1. Physical state: They are found in three states i.e. solid, liquid, and gas at normal temperature such as – solid- carbon (C), sulphur (S), iodine (I), ljquid – bromine (Br) and gas-oxygen (O₂), nitrogen (N₂), hydrogen (H₂).
2. Colour: Non-metals have variety of colours such as sulphur (yellow), chlorine gas (greenish yellow), phosphorous (red, white).
3. Lustre: Non-metals are non lustrous. They do not reflect light. Diamond and iodine are exceptions as these are lustrous.
4. Hardness: They are soft. Diamond is exception, it is the hardest non-metal found on earth.
5. Sonorous: They do not produce sound.
6. Density: They have less density.
7. Melting point: The have low melting point except diamond and graphite. Diamond and graphite (isotopes of carbon) have very high melting point.
8. Heat and electric conductivity: They are bad conductor of heat and electricity except graphite. It is a good conductor of electricity.
9. Brittle: When they are beaten with hammer, convert into power or pieces it is called brittleness.

Physical Properties of Non-metals

Physical State - Most of the non-metals exist in two of the three states of matter at room temperature: gases (oxygen) and solids (iodine, carbon, sulphur). These have no metallic lustre, (except iodine) and do not reflect light. (Except carbon in the form of diamond).

Nature - Non-metals are very brittle, and cannot be rolled into wires or pounded into sheets. Except- diamond is the hardest substance known.

Conduction - They are poor conductors of heat and electricity. (Except graphite conducts heat, both graphite & gas carbon conduct electricity.)

Electronegative Character - Non-metals have a tendency to gain or share electrons with other atoms. They are electronegative in character.

Reactivity - They generally form acidic or neutral oxides with oxygen.

Melting and Boiling Points – Non-metals have low melting and boiling points.

(i) Metal that exists in liquid state at room temperature → Mercury 

(ii) Metal that can be easily cut with a knife → Sodium, Potassium 

(iii) Metal that is the best conductor of heat → Silver, Gold 

(iv) Metals that are poor conductors of heat → Mercury and lead